I tried my luck with Vue's customer service team again today (yesterday, they told me it couldn't be refunded and that there were no tickets available, despite a few appearing on the website in all screens).

Today, after telling me that tickets are non-refundable, when I explained the situation, they were nice enough to allow me to purchase a new ticket for the screen I wanted (all the ones available on the website were available on their side too), and refund my old one. So, essentially, exchange my ticket